In a diplomatic game of chicken, a large Russian aid convoy rolled toward the Ukrainian border on Thursday — but it was heading toward a crossing controlled by pro-Russian rebels instead of a government post as Ukraine had demanded.

Ukraine's government threatened to block the convoy if the cargo could not be inspected and announced it was organizing its own aid shipment to the war-wracked separatist region of Luhansk.

The Russian convoy of more than 200 vehicles had been parked at a military depot in the southern Russian city of Voronezh since late Tuesday amid disagreement over how and where the aid could be delivered to eastern Ukraine, where government troops are battling armed separatists.

But on Thursday, the white-tarped trucks, some flying the red flag of Moscow and accompanied by military vehicles, drove down a winding highway through sunflower fields and green hills then turned west toward the rebel-held border crossing of Izvaryne.

But the trucks soon pulled off about 28 kilometres from the border and parked in a large field where dozens of beige tents had been set up. Drivers in matching delivery outfits got out and relaxed, making it unclear whether the convoy would cross into Ukraine later in the day or spend the night on Russian soil.

The route suggested Russia was intent on not abiding by a tentative agreement to deliver aid to a government-controlled border checkpoint in the Kharkiv region, where it could more easily be inspected by Ukraine and the Red Cross. Moscow has insisted it co-ordinated the dispatch of the goods, which it says range from baby food and canned meat to portable generators and sleeping bags, with the International Committee of the Red Cross.

Andriy Lysenko, a spokesman for Ukraine's National Security and Defence Council, said Ukraine would be forced to act if the Russians refused to allow a Red Cross inspection of its cargo. "In this case, movement of the convoy will be blocked with all the forces available," he said.

Although the Izvaryne border crossing remained in rebel hands, areas south of Luhansk have been bitterly fought over and the location of forces is in constant flux. It's unclear whether all the towns and villages from the border to Luhansk are still controlled by rebels.

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